The purpose of this contract is to provide for the continued operation and maintenance of the National Institute on Drug Abuse (NIDA) Medications Development Database (MDD). The database was developed for NIDA to serve as a reference source for both NIDA and research investigators in the area of drug abuse, and to facilitate the identification of therapeutic agents for the treatment of drug addiction. The information contained in the MDD includes chemical structures, physical constants, and receptor binding information, as well as pharmacological preclinical data, on compounds which are centrally active or have been shown to possess activity at neurotransmitters. This information was accumulated from published literature, NIDA grantees and other researchers in the area of drug abuse, the Committee on Problems of Drug Dependence and pharmaceutical sources. This contract will enable NIDA to continue to gather and store information from these sources, and will provide for the continued operation of the database through maintenance of the hardware and software systems, data entry, communication with the authorized user community, and training of new users.